we use those one-time-use plastic? stuff that comes in a "kleenex-box". Purpose is to keep the paste from the fingers. Although it�s seen that you won�t take Pb through your skin, it sticks to it (the skin and under your nails) and is hard to be removed through normal handwashing causing the danger of being swallowed with your next sandwich which is much more harmful. And what about the other stuff in your paste, I wouldn�t put it on my bread either.